package string;

public class ToUpperCaseDemo {
    public static void main(String[] args) {
        String str = "我爱Java";
       // System.out.println(str.toUpperCase());
        String upper = str.toUpperCase();//全大写
        System.out.println(upper);//我爱JAVA
        //System.out.println(str.toLowerCase());
        String lower = str.toLowerCase();//全小写
        System.out.println(lower);//我爱java
    }
}
